The backup and the "original" are fully identical. Before writing it down I just xor the original 2048bit key that results in a valid seed for electrum with a password and store that value as BIP39 encoded seed words. Xor that again with the valid password and you get the original and valid electrum seed back.
I tried to look up Xor but I don't really understand what that is.. I guess it is creating a hash and then reverse hash or something like that, so yeah, maybe I am missing something in regards to what you are doing since I don't really know how to xor anything... at least not so far in my bitcoin journey (or otherwise in my personal life - not that I know about.. maybe I had been XORing things without realizing that was what I was doing all this time).
..
An XOR gate implements an exclusive or, that is, a true output results if one, and only one, of the inputs to the gate is true.
..
Given that the key is basically just a very large integer number and given that any password (or a hash thereof) can also be represented by a equally large integer, you can xor the key(-number) K with the password(-number) P and get a new large number N.
Means K^P = N and N^P = K
Let's assume for the below example that we deal only with numbers up to 15 (4 bits), let K be 13 and let P be 9, the result of xoring them is 4 (see below):
13 = 1101
^
9 = 1001
=========
4 = 0100
Now if we take the "fake seed" N (4) and xor it again with the password P (9) we get again our key K (13):
9 = 1001
^
4 = 0100
=========
13 = 1101
To quote loosely from
Applied Cryptography: Xor is a extremly secure cryptographic algorithm under the assumption that they key is of perfect randomness and at least as long as the payload to encrypt.
That is not to say that the above described procedure is by any means anything even resembling serious cryptography, but it should delay the regular thug and win me some more time to secure the funds via backup.
But the procedure could be extended to work only on the seed and calculate the checksum itself. The N value would then not only look like a seed but be a valid seed and you could even transfer some smallish fund to that camouflage wallet and hope the thug just takes the few sats you left there and is happy with his loot.